Identification and Cross-reactivity Analysis of Sarcoplasmic-Calcium-Binding Protein: A Novel Allergen in Crassostrea angulata

Abstract

Oysters are an important shellfish group known to cause food allergy; however, knowledge of their sensitization components and cross-reactivity is limited. This study aimed to identify a novel allergen in Crassostrea angulata and investigate its cross-reactivity. To this end, a 20 kDa protein was purified from oyster and confirmed to be a sarcoplasmic-calcium-binding protein (SCP) by LC-MS/MS. A 537 bp open reading frame was obtained from oyster SCP total RNA, which encoded 179 amino acids, and was expressed in Escherichia coli. According to the circular dichroism results, digestion assay, and inhibition ELISA, the recombinant SCP (rSCP) exhibited similar physicochemical properties and IgG-binding activity to native SCP. rSCP displayed stronger IgE-binding activity by immunological method. Moreover, a different intensity of cross-reactivity and sequence homology were demonstrated between shellfish species. Collectively, these findings provide novel insight into shellfish allergens, which can be used to aid in the in vitro diagnosis of oyster-sensitized patients.

Aquatic food animals in the United States: Status quo and challenges

“…For example, six new allergenic proteins other than parvalbumin were identified in swordfish (Valverde‐Monge et al., 2018). A 20‐kDa sarcoplasmic calcium‐binding protein from oysters was recognized as a novel allergen and thought responsible for causing shellfish cross‐reactivity (Han et al., 2020). Lastly, the allergenicity may be unchanged or even increased after processing.…”

Newly defined allergens in the WHO/IUIS Allergen Nomenclature Database during 01/2019‐03/2021

“…Sera of 10 out of 10 oyster-allergic patients and sera of 8 out of 8 sea snail-allergic patients exhibited IgE reactivity against Cra a 4 and Rap v 2, respectively. 13,71 The clinical relevance of the first allergen described in eggplant, a member of the profilin family, is a striking example for the widely observed cross-reactivity of profilins. Thirty-six highly atopic patients with markedly elevated total IgE and a clinical history of eggplant allergy had a positive SPT to a raw eggplant extract and all patients' sera reacted to the recombinant Sola m 1.…”

“…Its immunogenicity was investigated with immunoblot and BAT. Another allergen from the EF‐hand family is Cra a 4, a sarcoplasmic calcium‐binding protein from the Pacific oyster 71 . The authors determined five epitope peptides of the allergen.…”

“…For two molluscs, the sea snail Rapana venosa (veined or Asian rapa whelk) and the Portuguese oyster ( Crassostrea angulata ), allergenic proteins were described for the first time. Sera of 10 out of 10 oyster‐allergic patients and sera of 8 out of 8 sea snail‐allergic patients exhibited IgE reactivity against Cra a 4 and Rap v 2, respectively 13,71 …”

Aptamer-Based Fluorescent Biosensor for the Rapid and Sensitive Detection of Allergens in Food Matrices

“…Studies have shown that although the spatial structure of AK is more complex than that of TM, damage to the spatial structure (treated by heat and pH) can reduce its sensitization [74][75][76]. In addition to the two major allergens mentioned above, the allergen sarcoplasmic calcium binding protein in the muscles of crustacean aquatic products has an EF hand structure similar to that of PV, which can induce 29-50% of shrimp allergic patients to be positive for Ig E binding [77]. In recent years, some new allergens, such as myosin light chain, troponin, triose phosphate isomerase, and paramyosin, which can cause mild allergic reactions, have also been isolated and identified [78,79].…”